It's not the ideal to have a single chick. But, it doesn't have to be a disaster. SOMETIMES, circumstances force it. My "house" chicken is spending her second winter in the house. Dottie is extremely uncomfortable around other chickens to the point of running away when everyone is free ranging outside.
When she's not in her crate (which used to house a Great Pyrenees, so she has plenty of space), she likes to wander around the house, pecking at anything and everything. Eventually, she will hop up on the soda, frequently with me, the dog and the cat, and snuggle in for a nap. I don't think she's unhappy.
I think if you stick with your plan, things will work out. Here's hoping both your ladies live long and healthy lives.